We are playing the Guess Game. The game is as follows:
I pick a number from 1 to n. You have to guess which number I picked.
Every time you guess wrong, I‘ll tell you whether the number is higher or lower.
You call a pre-defined API guess(int num) which returns 3 possible results (-1, 1, or 0):
-1 : My number is lower 1 : My number is higher 0 : Congrats! You got it!
Example:
n = 10, I pick 6. Return 6.
一个二分查找
// Forward declaration of guess API. // @param num, your guess // @return -1 if my number is lower, 1 if my number is higher, otherwise return 0 int guess(int num); class Solution { public: int guessNumber(int n) { long long start=1,end=n; long long mid=(start+end+1)/2; if(0==guess(start))return start; while(guess(mid)) { if(-1==guess(mid)) { end=mid-1; mid=(start+end+1)/2; } if(1==guess(mid)) { start=mid+1; if(0==guess(start))return start; mid=(start+end+1)/2; } } return mid; } };
LeetCode 374. Guess Number Higher or Lower
原文：http://www.cnblogs.com/csudanli/p/5891203.html